+let time_travel0 (sto,ali) =
+ let diff_len = List.length !storage - List.length sto in
+ let to_be_deleted,_ = HExtlib.split_nth diff_len !storage in
+ if List.length to_be_deleted > 0 then
+ List.iter NCicEnvironment.invalidate_item to_be_deleted;
+ storage := sto; local_aliases := ali
+;;
+
+let time_travel status = time_travel0 status#timestamp;;
+
+let replace status =